1. Field of the Invention
The present invention relates generally to image-to-paper registration setup of a printer and, more particularly, to a method, system and test sheet image bitmap for carrying out a scanner-and-processor based image-to-paper registration setup of a printer.
2. Description of the Related Art
With respect to most prior art printers, detection of image-to-paper registration errors is performed manually by the user. A registration test pattern is printed on an output sheet and the user visually examines the registration test pattern to determine the amount of any registration errors. After determining the amount of any registration errors, the user enters adjustment data into the printer via an operator panel. Adjustment of registration errors by manual inspection of registration marks and manual entry of adjustment data into the printer are inconvenient for user. Each adjustment step may involve multiple iterations of printing and measuring test images and adjusting imaging system parameters before registration error magnitudes are reduced to acceptable levels.
In the case of one current prior art printer, image-to-paper registration is set-up using a printed test pattern having registration marks which are referenced to the four edges of the sheet. However, in many cases, it is not always possible to print all the way to the edges of the page. Hence, in these cases, the reference marks may not always be visible, making it difficult to register the printer. The current prior art registration procedure is accomplished using iterative adjustment, significantly increasing the time necessary to register the printer, to be within the acceptable limits. Given that the registration marks are referenced to each edge of the sheet, the tolerance on the width of the sheet itself adds an additional variability to the accuracy of the adjustments.
One prior art approach to dealing with registration errors in a printer is disclosed in U.S. Pat. No. 6,763,199. Setup of image-to-paper registration is accomplished through use of an initial set of measurements made on a printed test pattern to determine and correct or adjust each of the independent registration errors. Registration marks employed on the test pattern are in the form of crosshairs positioned near corners of a rectangle. The measurements are taken with the crosshair registration marks constituting measurement starting points. The various measurements obtained from the registration test image are then entered into and stored by a controller in a memory. The controller can then access the measurements and supply them to a calculation circuit which performs the calculations using a set of algorithms and provides the results to a setup routine or circuit. The setup routine or circuit, under the control of the controller and in cooperation with an image forming engine of the printer, adjusts the registration altering elements of the printer to the extent necessary to perform the registration setup and stores data on the nature and extent of the adjustments.
While the approach of this patent might represent a step in the right direction for dealing with registration errors in a printer, there is still a need for an innovation that will make adjustments to compensate for image-to-paper registration errors in an alternative manner.